Optical fiber filter with ultra-wide tuning range

ABSTRACT

The present invention discloses an optical fiber filter with an ultra-wide tuning range, comprising an input optical fiber, a two-dimensional mechanical rotating mirror, a collimating and beam expanding system, two gratings, and an output optical fiber. The input optical fiber emits a multi-wavelength optical signal into the two-dimensional mechanical rotating mirror, the optical signal is reflected to the collimating and beam expanding system to form collimated beams, the collimated beams are incident on the gratings which generate dispersion to scatter different wavelengths to different angles, and lights of different diffraction angles are input into the output optical fiber by adjusting the two-dimensional mechanical rotating mirror. In the present invention, a two-dimensional mechanical rotating mirror is used to switch gratings of different wavebands, which can realize tuning of optical wavelengths in an ultra-wide range. The application scenarios are greatly expanded, the cost is reduced, and the optical path is simple, which can realize fast tuning. In addition, the number of channels is expanded by multiplexing the time and space of a rotating device.

TECHNICAL FIELD

The present invention belongs to the field of optical fiber communications and optical fiber sensing, and more particularly, to an optical fiber filter with an ultra-wide tuning range.

BACKGROUND

In long-distance and large-capacity communications, DWDM optical fiber communication plays a dominate role. With the explosive growth of network services, DWDM transmission channels are extending from the traditional 80 or 96 channels to 120 channels, even to L band. An optical channel performance monitor is an indispensable important device for system health in a DWDM optical communication system. A tunable optical fiber filter is the core optical engine of the optical channel performance monitor, and the working wavelength range also requires a corresponding extension. At present, the tuning range for mainstream tunable optical fiber filter wavelength on the market is 40˜50 nm. A single independent device cannot meet the ultra-wide C+L tuning range, and two independent devices have to be used to complete the tuning or scanning of the C or L band respectively. The disadvantage of this method is high cost and large volume.

SUMMARY OF THE INVENTION

In order to solve deficiencies in the prior art, the present invention provides an optical fiber filter with an ultra-wide tuning range that has low cost, a simple structure, stable performance, and high-reliability, which can realize a C+L, ultra-wide tuning range.

In order to realize the above objective, the following technical solutions are used in the present invention.

An optical fiber filter with an ultra-wide tuning range includes an input optical fiber, a two-dimensional mechanical rotating mirror, a collimating and beam expanding system, two gratings, and an output optical fiber. The input optical fiber emits a multi-wavelength optical signal into the two-dimensional mechanical rotating mirror, the optical signal is reflected to the collimating and beam expanding system to form collimated beams, the collimated beams are incident on the gratings which generate dispersion to scalier different wavelengths to different angles, and lights of different diffraction angles are input into the output optical fiber by adjusting the two-dimensional mechanical rotating minor.

Further, the input optical fiber, the output optical fiber, and the optical fiber circulator compose a dual optical fiber structure: first total reflection components are correspondingly arranged on front ends of the two gratings, and second total reflection components are correspondingly arranged on rear ends of the two gratings. Collimated beams from the collimating and beam expanding system are reflected by the first total reflection componentsand enter into the gratings, and optical signals from the gratings return to the optical fiber circulator along a retracing path through the second total reflection components and are output from the output optical fiber.

Further, the input optical fiber and the output optical fiber are two independent components, and there are two output optical fibers; the first total reflection components are correspondingly arranged on front ends of the two gratings, and groups of lenses are correspondingly arranged on rear ends of the two gratings. The two output optical fibers are arranged corresponding to two groups of lenses, and optical signals from the gratings are coupled into corresponding output optical fibers via the groups of lenses.

Further, the gratings are a multilevel cascade structure of a transmissive grating, a reflective grating or a group of the two.

Further, one dimension of the two-dimensional mechanical rotating mirror is used for wavelength tuning, and the other dimension is used to expand the wavelength tuning range to make it switchable between C-band and L-band gratings, so as to achieve an ultra-wide tuning range in the entire C+L bands; the two-dimensional mechanical rotating mirror can also adjust the power of the output optical signal.

The above technical solutions are used in the present invention, and have the following beneficial effects: a two-dimensional mechanical rotating mirror is used to switch gratings of different wavebands, which can realize tuning of optical wavelengths in an ultra-wide range. The application scenarios are greatly expanded, the cost is reduced, and the optical path is simple, which can realize fast tuning. In addition, the number of channels is expanded by multiplexing the time and space of a rotating device.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

FIG. 1 is a schematic diagram of Embodiment 1 according to the present invention;

FIG. 2 is a schematic diagram of Embodiment 2 according to the present invention;

FIG, 3 is a schematic diagram of Embodiment 3 according to the present invention; and

FIG. 4 is a schematic diagram of Embodiment 4 according to the present invention.

DETAILED DESCRIPTION

As shown in FIG. 1-4, in the present invention, an optical fiber filter with an ultra-wide tuning range includes input optical fiber 1, two-dimensional mechanical rotating mirror 3, collimating and beam expanding system 4, two gratings 7 and 8, and output optical fiber 2. Input optical fiber 1 emits a multi-wavelength optical signal into two-dimensional mechanical rotating mirror 3, the optical signal is reflected to collimating and beam expanding system 4 to form collimated beams, the collimated beams are incident on grating 7 or 8 which generate dispersion to scatter different wavelengths to different angles, and lights of different diffraction angles are input into output optical fiber 2 by adjusting two-dimensional mechanical rotating mirror 3.

In embodiment 1, as shown in FIG. 1, input optical fiber 1, output optical fiber 2, and optical fiber circulator 11 compose a dual optical fiber structure; first total reflection components 5 or 6 are correspondingly arranged on front ends of two gratings 7 and 8, and second total reflection components 9 or 10 are correspondingly arranged on rear ends of two gratings 7 and 8. Collimated beams from collimating and beam expanding system 4 are reflected by first total reflection components 5 or 6 and enter into gratings 7 or 8, and optical signals from gratings 7 or 8 return to optical fiber circulator 11 along a retracing path through second total reflection components 9 or 10 and are output from output optical fiber 2.

First total reflection components 5 and 6 and second total reflection components 9 and 10 may be total reflection mirrors or total reflection prisms.

The working principle is that: a multi-wavelength optical signal input by input optical fiber 1 is incident on two-dimensional mechanical rotating mirror 3, and the optical signal is reflected to collimating and beam expanding system 4 and is incident on a plane of gratings 7 or 8 via first total reflection components 5 or 6, and gratings 7 or 8 generate dispersion. Only the wavelength that satisfies the LITTROW condition obtains the maximum diffraction efficiency, and is reflected back to the optical fiber circulator through the corresponding total reflection mirror, and output through output optical fiber 2, so that the input light passes through grating 7 or 8 twice, and the bandwidth of the input spectrum is effectively compressed. If two-dimensional mechanical rotating mirror 3 is rotated, different rotation angles will have corresponding different wavelengths that meet the LITTROW condition and are reflected to collimating and beam expanding system 4, so as to achieve the purpose of tuning. Grating 7 or 8 is selected by a second rotation dimension of two-dimensional mechanical rotating mirror 3 being set at different angles. If two gratings 7 and 8 are set to different wavelength ranges, the tuning range of the filter can be expanded, thereby achieving an ultra-wide tuning range in the C+L band. In addition, the power of the output optical signal can be adjusted at the same time by rotating two-dimensional mechanical rotating mirror 3.

In Embodiment 2, as shown in FIG. 2, Embodiment 2 is based on Embodiment 1. If the second total reflection components and an optical fiber circulator shown in embodiment 1 are not used, the input optical fiber and output optical fiber are two independent components, and there are two output optical fibers. First total reflection components 5 or 6 are correspondingly arranged on front ends of two gratings 7 and 8, and groups of lenses 12 or 13 are correspondingly arranged on rear ends of two gratings 7 and 8. The two output optical fibers are arranged corresponding to two groups of lenses 12 or 13, and optical signals from gratings 7 or 8 are coupled into corresponding output optical fibers via the groups of lenses 12 or 13, thereby achieving an ultra-wide tuning range in the C+L band.

In Embodiment 3, as shown in FIG, 3, Embodiment 3 is based on Embodiment Optical signals of different wavelength ranges can be incident on two-dimensional mechanical rotating mirror 3 simultaneously via. optical fiber circulators 11 and 14. When two-dimensional mechanical rotating mirror 3 is rotated at a specific angle, the input light will directly return to the input optical fiber. Compared with Embodiment 1, synchronous timing of different bands can be achieved in Embodiment 3.

In Embodiment 4, as shown in FIG. 4, Embodiment 4 is based on Embodiments 1 and 3. Gratings 7,8 may be a multilevel cascade structure of transmissive gratings, reflective gratings or a combination of transmissive gratings and reflective gratings.

The implementation of the present invention is described above with reference to the accompanying drawings, but the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are illustrative rather than limiting the present invention, and those of ordinary skill in the art should understand that: it is still possible to modify the technical solutions described in the foregoing embodiments, or equivalently replace some or all of the technical features. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered in the scope of the claims and specification of the present invention. 

1. An optical fiber filter with an ultra-wide tuning range, comprising an input optical fiber, a two-dimensional mechanical rotating mirror, a collimating and beam expanding system, two gratings, and an output optical fiber; wherein the input optical fiber emits a multi-wavelength optical signal into the two-dimensional mechanical rotating mirror, the optical signal is reflected to the collimating and beam expanding system to form collimated beams, the collimated beams are incident on the gratings which generate dispersion to scatter different wavelengths to different angles, and lights of different diffraction angles are input into the output optical fiber by adjusting the two-dimensional mechanical rotating mirror.
 2. The optical fiber filter with an ultra-wide tuning range according to claim 1, wherein the input optical fiber, the output optical fiber, and the optical fiber circulator compose a dual optical fiber structure; first total reflection components are correspondingly arranged on front ends of the two gratings, and second total reflection components are correspondingly arranged on rear ends of the two gratings, collimated beams from the collimating and beam expanding system are reflected by the first total reflection components and enter into the gratings, and optical signals from the gratings return to the optical fiber circulator along a retracing path through the second total reflection components and are output from the output optical fiber.
 3. The optical fiber filter with an ultra vide tuning range according to claim 1, wherein the input optical fiber and the output optical fiber are two independent components, and there are two output optical fibers; first total reflection components are correspondingly arranged on front ends of the two gratings, and groups of lenses are correspondingly arranged on rear ends of the two gratings, the two output optical fibers are arranged corresponding to two groups of lenses, and optical signals from the gratings are coupled into corresponding output optical fibers via the groups of lenses.
 4. The optical fiber filter with an ultra-wide tuning range according to claim 1, wherein the gratings are a multilevel cascade structure of transmissive gratings, reflective gratings or a combination of transmissive gratings and reflective gratings
 5. The optical fiber filter with an ultra-wide tuning range according to claim 1, wherein one dimension of the two-dimensional mechanical rotating mirror is used for wavelength tuning, and the other dimension is used to expand the wavelength tuning range to make it switchable between C-band and L-band gratings, so as to achieve an ultra-wide tuning range in the entire C+L bands; the two-dimensional mechanical rotating mirror can also adjust the power of the output optical signal. 